Adrenergic and Cholinergic receptors Flashcards
Adrenergic receptors bind
Catecholamines (NE and EPI)
Catecholamines
NE and EPI
Steps to synthesize catecholamines
Tyrosine to DOPA to dopamine to NE to EPI
Where does synthesis of catecholamines occur
Nerve terminal
Where are catecholamines stored
Synaptic vesicles
Location of adrenergic receptors
Postsynaptic membrane
How catecholamines are inactivated
Reuptake with VMAT or degradation with MOA
Types of adrenergic receptors
Alpha and Beta
What type of receptor are adrenergic receptors
G-coupled protein
Types of alpha receptors
Alpha 1 and Alpha 2
How alpha 1 stimulates
Post-synaptically stimulates phospholipase C and causes vasoconstriction/pupil dilation
Activation of alpha 1 causes
Contraction of muscles
Alpha 1 receptors located at…
Vasculature
Dilator pupillae
Internal urethral sphincter
Alpha 1 stimulation of vasculature
Vasoconstriction - increased BP and increase in TPR
Alpha one dilator pupillae
Pupil dilation
Alpha 1 on internal ureteral sphincter
Contraction
Alpha 2 receptor location
NE nerve terminal
Alpha 2 action
Inhibitory, activation of these receptors decreases amount of NE released
Beta adrenergic receptor type
G protein coupled
What do Beta receptors mediate
Relaxation or decreased activity
Types of beta receptors
Beta 1 and Beta 2
Where are beta 1 receptors
Heart
Beta 1 receptors on heart
Act on SA and AV nodes to increase HR and conduction velocity
Increase contractility and stroke volume
Beta 2 receptors location
Vascular
Bronchial smooth muscle
Detrusor (bladder)
Beta 2 on vascular
Vasodilation decreases TPR and increases CO
Beta 2 bronchial
Bronchodilation
Beta 2 bladder
Relaxation (stretch and fill)
Impact level of NE and EPI on adrenergic receptors
NE stimulates alpha more than beta
EPI stimulates alpha and beta equally
Removal of NE and EPI
NorEpinephrine transporter (NET
Takes up from the synapse
Diffusion
Degradation into inactive metabolites by MOA and COMT
Time of activation NE
Seconds and rapid reuptake and diffusion
Time of activation EPI
Several minutes
ABCD
Alpha constrict with NE
Beta dilates with epi
Cholinergic receptor
Binds ACh
Types of cholinergic receptors
Muscarinic and nicotinic
Synthesis of ACh
Acetyl coA and choline via ChAT
Where is ACh stored
Vesicles in the terminal axon
How is ACh released
AP causes Ca influx and SNARE complex activation which fuses the vesicle containing ACh
Inactivation of ACh through
Acetylcholinesterase
What type of channel is nicotinic
Ligand gated
Nicotinic receptor location
Neuromuscular junction
Activation of nicotinic receptor
Depolarizes skeletal muscle causing contraction
Nicotinic neuronal receptor location
ANS ganglia
Adrenal medulla
CNS
Nn ANS ganglia
Depolarizes post synaptic neurons and mediates effects of pre-ganglionic ANS neurons
Nn Adrenal medulla
Catecholamine release
Muscarinic receptor type
G protein coupled receptor
Overall action of muscarinic receptors
Parasympathetic innervation
Types of muscarinic receptors
M2 and M3
Location of M2 receptors
Heart
Activation of M2 receptor
SA and AV node to decrease HR and conduction velocity
Increasing vagal tone to elongate AP slope
Location of M3 receptors
Sweat glands
Respiratory system
GI tract
Urinary bladder
Eye
M3 sweat glands
Secretion (only one that is sympathetic ACh activation)
M3 respiratory system
Bronchoconstriction and increased secretions
M3 GI tract
Increase salivation, secretion, peristalsis
Relax sphincters
M3 Urinary bladder
Urinate
Contract bladder and relax sphincter
M3 eye
Contraction (pupil constriction)
Tear production
AChe cleaves into
Acetate ion and choline
AChR
Acetylcholinesterase is adjacent to cholinergic receptors and is primary way ACh is terminated